At the time of development of the integration, the documentation
https://docs.google.com/document/d/1f_KABuskIAdyFRbTKfQyJO_YchmHy3UPudsC9l3R1-A/... was used, where the key generation method and its transmission in the cid parameter are specified
Now the supplier has changed the API, including the old alternative one, in order to transmit the key (the secret key that can be found on the website, in your account, in the API section).
As far as I understand, there is a refinement in the integration / action that provides for specifying the Key in the final form. Please update this setting so that it is displayed in the appropriate section of CRM.